ABC /ˌeɪ biː ˈsiː/ BrE AmE noun
1 . [singular] British English , ABCs [plural] American English the letters of the English alphabet as taught to children
2 . the ABC of something British English , the ABCs of something American English the basic facts about a particular subject:
the ABCs of your computer
3 . (the American Broadcasting Company) one of the national television companies in the US
4 . (the Australian Broadcasting Corporation) the national public television company of Australia